A quarter of the CO2 emitted into the atmosphere by humans ends up in the oceans where it forms carbonic acid, causing the ocean’s pH value to decrease and its chemistry to change. This drop in acidity leads to a shortage of carbonate ions which are critical for shell and skeleton growth for many marine species.
When the pH value reaches a certain level, it becomes difficult for organisms like corals, shellfish, and plankton to grow and survive, altering ocean ecosystems and potentially reducing fish stocks. Compared to preindustrial times, the acidity has already increased by 30%.